US 11,742,745 B2
Method for identifying the filter inductor of a grid inverter
Roland Pieler, Wels-Thalheim (AT); Michael Rothböck, Wels-Thalheim (AT); Stefan Wieser, Wels-Thalheim (AT); and Harald Kreuzer, Wels-Thalheim (AT)
Assigned to FRONIUS INTERNATIONAL GMBH, Pettenbach (AT)
Appl. No. 17/783,854
Filed by Fronius International GmbH, Pettenbach (AT)
PCT Filed Dec. 9, 2020, PCT No. PCT/EP2020/085268
§ 371(c)(1), (2) Date Jun. 9, 2022,
PCT Pub. No. WO2021/116166, PCT Pub. Date Jun. 17, 2021.
Claims priority of application No. 19214654 (EP), filed on Dec. 10, 2019.
Prior Publication US 2023/0051498 A1, Feb. 16, 2023
Int. Cl. H02M 7/5387 (2007.01); H02M 1/12 (2006.01); G01R 27/26 (2006.01)
CPC H02M 1/126 (2013.01) [G01R 27/2611 (2013.01); H02M 7/53871 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A method for operating an inverter, the method comprising:
via a switching unit of the inverter, applying an AC voltage to a phase line in which a filter inductor is arranged,
determining characteristic values of a coil current (iL) and a coil voltage (uL) of the filter inductor in the region of a plurality of measurement points, wherein at least two measurement points are together located on at least one flank of a current ripple,
determining, from the characteristic values, a first value of the inductance (L(ILy)) of the filter inductor for a first value of the coil current (ILy),
wherein the method further comprises:
determining at least one further value of the inductance of the filter inductor for at least one further value of the coil current,
determining at least one inductance profile of the filter inductor with respect to the coil current, using the determined first value of the inductance (L(ILy)) of the filter inductor, and using the at least one further determined value of the inductance of the filter inductor, wherein the inductance profile describes a dependency of the values of the inductance (L(ILy)) of the filter inductor on the coil current,
controlling the switching unit of the inverter, via a control unit, to generate an alternating current in the phase line, wherein at least one parameter of the control is continuously adapted to the momentary value of the inductance according to a determined current-dependent inductance profile,
wherein the inductance profile is determined before the inverter is first put into operation, and/or at scheduled intervals before a, or before each, startup of the inverter.